Trane RT-PRC007-EN manual Controls, VAV Units Only

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Controls

VAV Units Only

Sequence of Operation

1

Supply Air Pressure Control

Inlet GuideVane Control

Inlet guide vanes are driven by a modulating 2-10 vdc signal from theVAV Module. A pressure transducer measures duct static pressure, and the inlet guide vanes are modulated to maintain the supply air static pressure within an adjustable user-defined range. The range is determined by the supply air pressure setpoint and supply air pressure deadband, which are set through a unit mounted potentiometer.

Inlet guide vane assemblies installed on the supply fan inlets regulate fan capacity and limit horsepower at lower system air requirements. When in any position other than full open, the vanes pre-spin intake air in the same direction as supply fan rotation. As the vanes approach the full-closed position, the amount of “spin” induced by the vanes increases at the same time that intake airflow and fan horsepower diminish. The inlet guide vanes will close when the supply fan is shut down.

Supply Air Static Pressure Limit

The opening of the inlet guide vanes and VAV boxes are coordinated, with respect to time, during unit start up and transition to/from Occupied/Unoccupied modes to prevent overpressurization of the supply air ductwork. However, if for any reason the supply air pressure exceeds the fixed supply air static pressure limit of 3.5” W.C., the supply fan is shut down and the inlet guide vanes are closed.The unit is then allowed to restart four times. If the overpressurization condition occurs on the fifth time, the unit is shut down and a manual reset diagnostic is set and displayed at any of the remote panels with LED status lights or communicated to the Integrated Comfort system.

Variable Frequency Drives (VFD) Control

Variable frequency drives are driven by a modulating 0-10 vdc signal from the VAV module. A pressure transducer measures duct static pressure, and the VFD is modulated to maintain the supply air static pressure within an adjustable user-defined range. The range is determined by the supply air pressure setpoint and supply air pressure deadband, which are set through a unit mounted potentiometer. Variable frequency drives provide supply fan motor speed modulation. The drive will accelerate or decelerate as required to maintain the supply static pressure setpoint. When subjected to high ambient return conditions the VFD shall reduce its output frequency to maintain operation. Bypass control is offered to provide full nominal airflow in the event of drive failure.

2

Supply AirTemperature Controls

Cooling/Economizer

During occupied cooling mode of operation, the economizer (if available) and primary cooling are used to control the supply air temperature.The supply air temperature setpoint is user-defined at the unit mountedVAV Setpoint Panel or at the remote panel. If the enthalpy of the outside air is appropriate to use “free cooling,” the economizer will be used first to attempt to satisfy the supply setpoint.

On units with economizer, a call for cooling will modulate the fresh air dampers open.The rate of economizer modulation is based on deviation of the discharge temperature from setpoint, i.e., the further away from setpoint, the faster the fresh air damper will open. Note that the economizer is only allowed to function freely if ambient conditions are below the enthalpy control setting or below the return air enthalpy if unit has comparative enthalpy installed. If outside air is not suitable for “economizing,” the

fresh air dampers drive to the minimum open position. A field adjustable potentiometer on the Unitary Economizer Module,Tracer®, or a remote potentiometer can provide the input to establish the minimum damper position.

At outdoor air conditions above the enthalpy control setting, primary cooling only is used and the fresh air dampers remain at minimum position.

If the unit does not include an economizer, primary cooling only is used to satisfy cooling requirements.

Supply Air Setpoint Reset

Supply air reset can be used to adjust the supply air temperature setpoint on the basis of a zone temperature, return air temperature, or on outdoor air temperature. Supply air reset adjustment is available on the unit mountedVAV Setpoint Panel for supply air cooling control.

a

Reset Based on Outdoor AirTemperature

Outdoor air cooling reset is sometimes used in applications where the outdoor temperature has a large effect on building load. When the outside air temperature is low and the building cooling load is low, the supply air setpoint can be raised, thereby preventing subcooling of critical zones. This reset can lower usage of primary cooling and result in a reduction in primary cooling energy usage.

There are two user-defined parameters that are adjustable through the VAV Setpoint Panel: reset temperature setpoint and reset amount.The amount of reset applied is dependent upon how far the outdoor air temperature is below the supply air reset setpoint.The amount is zero where they are equal and increases linearly toward the value set at the reset amount input.The maximum value is 20 F. If the outdoor air temperature is more than 20 F below the

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RT-PRC007-EN

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Contents Packaged Rooftop Air Conditioners Introduction American Standard IncContents Standard Features Features and BenefitsOptional Features Proven DesignThroughTesting and Research Trane 3-DScroll CompressorSimple Design with 70% Fewer Parts LowTorque VariationFeatures Benefits Quality and ReliabilityMicro Controls MicroRigorousTesting Ease of InstallationSingle Point Power FC Fans with Inlet GuideVanesEasy to Service ValueVariTrac Application Recommendations Power Exhaust Fan Exhaust Air OptionsBarometric Relief Dampers Altitude CorrectionsClearance Requirements Acoustical ConsiderationsDuct Design Selection Procedure Supply Air FanAir Delivery Procedure Electric Heating SystemNatural Gas Heating System Unit Electrical RequirementsModel Number Description General Data Table GD-1 General Data 27 1/2 30 TonsTable GD-2- General Data 35-40Ton Table GD-3- General Data 50Ton Table PD-1- Enthalpy of Saturated AIR Performance Adjustment FactorsTable PD-3 Gas Heating Capacity Altitude Correction Factors Table PD-4 27 1/2 Ton Gross Cooling Capacities MBh Performance DataTable PD-5- 30Ton Gross Cooling Capacities Mbh Table PD-6 35Ton Gross Cooling Capacities Mbh Table PD-7 40Ton Gross Cooling Capacities MbhTable PD-8 50Ton Gross Cooling Capacities MBh Table PD-10 Available Electric Heat KW Ranges Table PD-9 Electric Heat AirTemperature RiseTable PD-11 Natural Gas Heating Capacities Table PD-12 Supply Fan Performance 27½ 35Ton Static Pressure in. wg1Table PD-13 Supply Fan Performance 40 and 50Ton Heating System Filters2 Nominal Table PD-14 Component Static Pressure Drops in.W.G.1Gas Heat Electric Heat3 ID Coil 20 HP Table PD-15 Supply Air Fan Drive SelectionsNominal Drive Table PD-16- Power Exhaust Fan Performance Controls VAV Units OnlyCV Units Only Unoccupied ZoneTemperature Control Cooling and Heating Supply AirTemperingAuto Changeover ConventionalThermostat InterfaceOccupied/Unoccupied Switching Fan Failure SwitchCoil Freeze Protection Frostat Night Setback SensorsElectrical Data Electrical Service SizingSet 2. Rooftop units with Electric Heat Table ED-2 27½-50Ton Electrical Service Sizing Data1 Dimensional Data Figure DD-1 27 1/2 35Tons TC,TE,YC Low HeatDimensional Data Figure DD-3 40-50Tons TC,TE,YC Low & High Heat Dimensional Field Installed SensorsConstant CV and VAV Integrated Comfort System SensorsWeights TableW-2 Point Loading AverageWeight1TableW-3 ComponentWeights TableW-4 Minimum Operating Clearances for Unit InstallationMechanical Specifications Unit Options Accessories LP Conversion Kit 20-60Ton Literature Order Number File Number PL-RT-TC/TE/YC-27½ 50-TONS-PRC0007-EN-10-2001

RT-PRC007-EN specifications

The Trane RT-PRC007-EN is a part of Trane’s highly regarded line of air-cooled chillers, designed to provide exceptional performance and efficiency for a variety of commercial applications. This model is known for its robust engineering and cutting-edge technologies, making it a favored choice among facility managers and HVAC professionals.

One of the key features of the RT-PRC007-EN is its energy efficiency. Its advanced compressor design, alongside innovative heat exchanger technology, allows it to achieve significant energy savings, meeting or exceeding standards set by the Department of Energy. This efficiency not only results in lower operational costs but also contributes to a smaller carbon footprint, making it an environmentally friendly choice.

The chiller is equipped with variable speed compressors which adjust their output in relation to the cooling demand. This feature ensures optimal performance at all times, reducing energy consumption during partial load operations. Additionally, the RT-PRC007-EN incorporates Trane's unique Adaptive Control technology. This intelligent control system continuously monitors system parameters and environmental conditions, optimizing performance in real-time to ensure reliable operation.

Another standout characteristic of the RT-PRC007-EN is its quiet operation. The inclusion of sound-dampening technology and strategically placed acoustic insulation allows this chiller to operate with minimal noise, making it suitable for installations in noise-sensitive environments like hospitals or schools.

Durability is another hallmark of the RT-PRC007-EN. Built with high-quality materials, it is designed to withstand harsh operating conditions. Its corrosion-resistant components ensure longevity and reduce the need for extensive maintenance, making it a reliable choice for operators.

Lastly, the RT-PRC007-EN comes with a variety of customization options, including different refrigerant types, control systems, and capacity configurations. This flexibility allows it to adapt to the specific needs of different applications and building designs.

In summary, the Trane RT-PRC007-EN represents a fusion of efficiency, reliability, and advanced technology, making it an excellent option for those seeking a cutting-edge air-cooled chiller for their commercial HVAC needs.
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